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Expansion Bus Module (EBM)
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The expansion bus module (EBM) is a standalone module used to bond out both general-purpose input/output
pins and expansion bus interface pins. The module supports 8- and 16-bit expansion bus memory interface
mappings, as well as mapping of the following expansion bus signals:
22-bit address bus (EBADDR[21:0]) for x8, 19-bit address bus (EBADDR[18:0]) for x16
8- or 16-bit data bus (EBDATA[7:0]or EBDATA[15:0])
Two write strobes (EBWR[1:0])
Two memory chip selects (EBCS[6:5])
One output enable (EBOE)
One external hold signal for interfacing to slow memories (EBHOLD)
Table 7 shows the multiplexing of I/O signals with the expansion bus interface signals. The mapping of these
pins varies depending on the memory mode.
Table 7. Expansion Bus Multiplex Mapping(1)
EXPANSION BUS MODULE PINS(2)
GIO
x8
x16
GIOB[0]
EBDMAREQ[0]
GIOC[0]
EBOE
GIOC[2:1]
EBWR[1:0]
GIOC[4:3]
EBCS[6:5]
GIOD[5:0]
EBADDR[5:0]
GIOE[7:0]
EBDATA[7:0]
GIOF[7:0]
EBADDR[13:6]
EBDATA[15:8]
GIOG[7:0]
EBADDR[21:14]
EBADDR[13:6]
GIOH[4:0]
–
EBADDR[18:14]
GIOH[5]
EBHOLD
(1)
These mappings are controlled by the EBM mux control registers B–H (EBMXCRB–EBMXCRH) and
the EBM control register 1 (EBMCR1). For GPIO functions, use GIODIRx, GIODINx, GIODOUTx,
GIODSETx, and GIODCLRx. For more detailed information, see the TMS470R1x General-Purpose
Input/Output (GIO) Reference Guide (literature number SPNU192) and the TMS470R1x Expansion
Bus Module (EBM) Reference Guide (literature number SPNU222).
(2)
x8 refers to size of memory in 8-bits; x16 refers to size of memory in 16-bits.
Table 8 lists the names of the expansion bus interface signals and their functions.
Table 8. Expansion Bus Pins
PIN
DESCRIPTION
EBDMAREQ
Expansion bus DMA request
EBOE
Expansion bus output enable
Expansion bus write strobe. EBWR[1] controls
EBWR
EBDATA[15:8] and EBWR[0] controls EBDATA[7:0].
EBCS
Expansion bus chip select
EBADDR
Expansion bus address
EBDATA
Expansion bus data
Expansion bus hold: an external device connected to
EBHOLD
the expansion bus may assert this signal to add wait
states to an expansion bus transaction.
Copyright 2005–2008, Texas Instruments Incorporated
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